Method for producing a light emitting device

ABSTRACT

A method for producing a light emitting device includes a first bonding step including disposing a first bonding member a mounting substrate, placing a light emitting element on the mounting substrate such that the first bonding member is located between a mounting face of the light emitting element and the mounting substrate, and hardening the first bonding member thereby bonding the light emitting element and the mounting substrate such that, in a plan view, an entirety of the first bonding member is contained within an area of the mounting face of the light emitting element; and a second bonding step including disposing a second bonding member on the upper face of the mounting substrate such that, in a plan view, the second bonding member is located at at least a portion of an outer edge of the mounting face of the light emitting element, and hardening the second bonding member.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/078,566, filed Mar. 23, 2016, which claims priority under 35U.S.C. §119 to Japanese Patent Application No. 2015-065533, filed Mar.27, 2015, the contents of which are incorporated herein by reference intheir entireties.

BACKGROUND

The present disclosure relates to a method for producing a lightemitting device.

When a semiconductor light emitting element, such as an LED (lightemitting diode), is mounted on a mounting substrate, the light emittingelement and the mounting substrate are bonded together using a diebonding material, such as a resin or solder. For example, JapaneseUnexamined Patent Application Publication No. 2010-205775 (PatentDocument 1) discloses light emitting elements mounted by using a diebonding resin as a die bonding material. More specifically, in caseswhere a liquid or paste die bonding resin containing a thermosettingresin is employed as a die bonding material, light emitting elements arebonded to a mounting substrate by applying the die bonding resin on themounting substrate, followed by placing the light emitting elements onthe mounting substrate, and curing the die bonding material.

When a solder paste is employed as a die bonding material, lightemitting elements are bonded to a mounting substrate by applying thesolder paste on the mounting substrate, followed by placing the lightemitting elements on the mounting substrate, melting the solder byheating using a reflow furnace, and solidifying the molten solder bycooling.

SUMMARY

The method for producing a light emitting device according to oneembodiment is for producing a light emitting device, which includes amounting substrate and a light emitting element bonded to the mountingsubstrate and having electrodes on its upper face. The method includes afirst bonding step of placing a first bonding material in a liquid orpaste form on the upper face of the mounting substrate, placing thelight emitting element so that its mounting face opposes the mountingsubstrate via the first bonding material, and hardening said firstbonding material thereby bonding together the light emitting element andthe mounting substrate so that the first bonding material is disposed inthe area contained within the mounting face of the light emittingelement in a plan view; and a second bonding step of placing a secondbonding material in a liquid or paste form on the upper face of themounting substrate at least in one section of the outer edge of themounting face of light emitting element in a plan view, and hardeningthe second bonding material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of the light emitting deviceconstruction according to one embodiment.

FIG. 2A is a schematic plan view of the light emitting deviceconstruction according to the embodiment.

FIG. 2B is a schematic sectional view of the light emitting deviceconstruction according to the embodiment along line IIB-IIB indicated inFIG. 2A.

FIG. 3A is a schematic plan view of the light emitting elementconstruction employed in the light emitting device according to theembodiment.

FIG. 3B is a schematic sectional view of the light emitting elementconstruction employed in the light emitting device according to theembodiment along line IIIB-IIIB indicated in FIG. 3A.

FIG. 4 is a flowchart showing the steps in the method for producing alight emitting device according to the embodiment.

FIG. 5A is a sectional view schematically showing the first bondingmaterial disposing step in the method for producing a light emittingdevice according to the embodiment.

FIG. 5B is a sectional view schematically showing the light emittingelement placing step in the method for producing a light emitting deviceaccording to the embodiment.

FIG. 5C is a sectional view schematically showing the first bondingmaterial hardening step in the method for producing a light emittingdevice according to the embodiment.

FIG. 6A is a sectional view schematically showing the second bondingmaterial disposing step in the method for producing a light emittingdevice according to the embodiment.

FIG. 6B is a sectional view schematically showing the second bondingmaterial hardening step in the method for producing a light emittingdevice according to the embodiment.

FIG. 7A is a schematic plan view showing the state immediately afterdispensing the second bonding material in the second bonding materialdisposing step in the method for producing a light emitting deviceaccording to the embodiment.

FIG. 7B is a schematic plan view showing the state in which the secondbonding material has been spread in the second bonding materialdisposing step in the method for producing a light emitting deviceaccording to the embodiment.

FIG. 8A is a sectional view schematically showing the wiring step in themethod for producing a light emitting device according to theembodiment.

FIG. 8B is a sectional view schematically showing the light reflectorforming step in the method for producing a light emitting deviceaccording to the embodiment.

FIG. 8C is a sectional view schematically showing the sealing step inthe method for producing a light emitting device according to theembodiment.

DESCRIPTION

An embodiment of the invention will be described below with reference tothe drawings. The following embodiment, however, exemplify method ofproducing a light emitting device and a light emitting device for thepurpose of embodying the technical concepts of the invention, and do notlimit the invention. The dimensions, materials, and shapes of theconstituent elements, as well as the relative positioning thereof,described in the embodiment are offered to merely as examples, and arenot intended to limit the scope of the invention to those describedunless otherwise specifically noted. The sizes of the components, theirpositional relationship, or the like, shown in the drawings might beexaggerated for clarity of explanations. In the explanations givenbelow, moreover, the same designations and reference numerals indicatethe components that are identical or of the same nature, for which theexplanations will be omitted when appropriate.

In conventional processes, such as that disclosed in Patent Document 1,however, the light emitting elements are floating atop the liquid diebonding resin before curing, or on the molten solder, during themounting process. For this reason, the positions of the light emittingelements might occasionally shift within the range where the die bondingmaterial is applied before the die bonding material is hardened.Moreover, in order for the light emitting elements to be securely joinedwith the mounting substrate, it is preferable to apply the die bondingmaterial in wider areas than the mounting faces of the light emittingelements. However, the range of movement of the light emitting elementsis increased as the amount of the die bonding material is increased.

As such, when using a die bonding material during mounting in theconventional processes, it was difficult to bond the light emittingelements by positioning them with high precision. Moreover, when thelight emitting elements were arranged at narrow intervals in highdensity, the die bonding material ended up being continuously disposedover a wide range. This made it even more difficult to bond the lightemitting elements with high positional accuracy.

An object of certain embodiments of the present invention is to providea method for producing a light emitting device having light emittingelements bonded to the mounting substrate that is capable of highprecision positioning when bonding the light emitting elements to themounting substrate.

According to the method for producing a light emitting device accordingto one embodiment, a light emitting element is bonded to the mountingsubstrate using a first bonding material disposed in the area containedwithin the mounting face of the light emitting element in a plan view,followed by bonding the outer edge of the mounting face of lightemitting element to the mounting substrate using a second bondingmaterial. Thus, the light emitting element can be bonded to the mountingsubstrate with high positional accuracy.

Embodiment 1

Structure of Light Emitting Device

A structure of the light emitting device according to an embodiment willbe explained with reference to FIGS. 1, 2A, and 2B. For the sake ofconvenience, an outer shapes of a light reflector 6 and a sealing member7 are indicated by a two-dot chain line and dashed line, respectively,in the plan view shown in FIG. 2A to allow the interior to be viewed. InFIG. 2B, moreover, the detailed structure of a light emitting element 1is omitted, but it has an n-side electrode 13 and a p-side electrode 14on an upper face side, and a substrate 11 on the lower face side. Thesame is true for the light emitting elements 1 shown in FIGS. 5B to 6Band 8A to 8C discussed later.

A light emitting device 100 is constructed with plural light emittingelements 1 arranged in an array and mounted on a mounting substrate 2.In this embodiment, more specifically, 18 light emitting elements 1 arearranged in 6 rows and 3 columns. The light emitting elements 1 areindividually bonded to an upper face of the mounting substrate 2 usingbonding member 3 comprising a first bonding member 31 and a secondbonding member 32. On the upper face of the mounting substrate 2, awiring pattern comprising a positive electrode 22, a negative electrode23, and a relay wiring section 24 is disposed so as to surround a regionin which the light emitting elements 1 are arranged. The light emittingelements 1 are electrically connected to one another, and to the wiringpattern, using wires 4 so that the light emitting elements 1 emit lightwhen an external power supply is connected to the positive electrode 22and the negative electrode 23. Moreover, a protective element 5 isprovided between the positive electrode 22 and the negative electrode23. A light reflector 6 is disposed so as to surround the region inwhich the light emitting elements 1 are arranged, and the regionsurrounded by the light reflector 6 is filled with a sealing member 7 toseal the light emitting elements 1 and wires 4.

Neither an outer shape of the mounting substrate 2 nor an outer shape ofthe array of the light emitting elements 1 is limited to a rectangle,and it can suitably be a circular or polygonal shape. The light emittingelements 1 may be arranged in a two-dimensional array, and may bedisposed in a one-dimensional array, or may be a single piece.

Each constituent element will be sequentially explained in greaterdetail below.

The light emitting elements 1 in this embodiment each has a pair ofelectrodes, n-side electrode 13 and p-side electrode 14, on its upperface, and its lower face is bonded to the upper face of a mountingsubstrate 2 using a first bonding member 31 and a second bonding, member32.

In this embodiment, as shown in FIG. 2A, the light emitting elements 1arranged in the upper three rows are oriented to have the n-sideelectrodes 13 on the right hand side and the p-side electrodes 14 on theleft hand side, whereas the light emitting elements 1 arranged in thelower three rows are oriented to have the n-side electrodes 13 on theleft hand side and the p-side electrodes 14 on the right hand side. Thethree light emitting elements 1 in each row of the upper three rows areconnected in series in the row-wise (horizontal) direction between thewiring section 22 b of the positive electrode 22 and the relay wiringsection 24 by wires 4. The three light emitting elements 1 in eachcolumn of the upper three rows are connected in parallel. The threelight emitting elements 1 in each row of the lower three rows areconnected in series in the row-wise (horizontal) direction between thewiring section 23 b of the negative electrode 23 and the relay wiringsection 24 by wires 4. The three light emitting elements 1 in eachcolumn of the three lower rows are connected in parallel. Accordingly,the 18 light emitting elements 1 are connected to be equivalent to acircuit where three serially connected sets, each set having sixserially connected light emitting elements 1, are connected to thepositive electrode 22 and the negative electrode 23 in parallel.

Here, an example of the construction of the light emitting element 1will be explained with reference to FIGS. 3A and 3B.

For the light emitting elements 1 in this embodiment, semiconductorlight emitting elements, such as LEDs, can suitably be used. The lightemitting elements 1 in this embodiment are each formed in a rectangle ina plan view, and include a substrate 11, a semiconductor stack 12, ann-side electrode 13, a p-side electrode 14, and a protective film 15,respectively. The light emitting elements 1 in this embodiment each hasthe semiconductor stack 12 having an LED (light emitting diode)structure on one principal face of the substrate 11, and further has then-side electrode 13 and p-side electrode 14 on the surface of thesemiconductor stack 12, thereby being suitable for the mounting methodusing the upper face side of the light emitting element as the emissionface.

The substrate 11 is a component that supports the semiconductor stack12. Example materials that can be employed include sapphire, SiC, or thelike. The substrate 11 may also be, for example, a substrate enablingepitaxial growth of the semiconductor stack 12. In the case of formingthe semiconductor stack 12 using a nitride semiconductor, such as GaN(gallium nitride), for example, sapphire can suitably be used.

The semiconductor stack 12 is constructed by stacking on one principalface (the upper face) of the substrate 11 an n-type semiconductor layer12 n, an active layer 12 a, and a p-type semiconductor layer 12 p so asto emit light when an electrical current is supplied between the n-sideelectrode 13 and the p-side electrode 14.

The semiconductor stack 12 has a region where the p-type semiconductorlayer 12 p and the active layer 12 a are absent, i.e., the region 12 bwhere the n-type semiconductor layer 12 n is exposed. The n-sideelectrode 13 is disposed in the region 12 b where the n-typesemiconductor layer 12 n is exposed, and is electrically connected tothe n-type semiconductor layer 12 n.

A light transmitting electrode 141 is disposed substantially across theentire upper face of the p-type semiconductor layer 12 p, and a padelectrode 142 is further disposed in one section of the upper face ofthe light transmitting electrode 141.

The n-side electrode 13 is a negative polarity side pad electrode forsupplying electrical current to the light emitting element 1 from theoutside. For the n-side electrode 13, Cu, Au, or an alloy having eithermetal as its main component, for example, can be used so as to besuitable for external connection by wire bonding, or the like.

The p-side electrode 14 is disposed on the upper face of the p-typesemiconductor layer 12 p to be electrically connected to the p-typesemiconductor layer 12 p, and is a positive polarity side electrode forsupplying electrical current from the outside. The p-side electrode 14has a structure where a light transmitting electrode 141 and a padelectrode 142 are stacked.

The light transmitting electrode 141 located on the lower side of thep-side electrode 14 is disposed so as to cover substantially the entireupper face of the p-type semiconductor layer 12 p. The lighttransmitting electrode 141 functions as an electrical current diffusionlayer for diffusing the electrical current supplied from the outside viathe pad electrode 142 to substantially the entire surface of the p-typesemiconductor layer 12 p. The light transmitting electrode 141 can beformed with a conductive metal oxide. For example, ITO (Sn-doped In₂O₃),which is a high conductivity material having high light transmittancewith respect to the visible light (in the visible range), can suitablybe used.

The pad electrode 142 located on the upper side of the p-side electrode14 is disposed in one section of the upper face of the lighttransmitting electrode 141, and is a layer for external connection. Asshown in FIG. 3A, the pad electrode 142 comprises an external connectionsection 142 a for enabling external connection by wire bonding, or thelike, and an extended section 142 b which extends from the externalconnection section 142 a for more efficient diffusion of the electricalcurrent. For the pad electrode 142, as in the case of the n-sideelectrode 13, Cu, Au, or an alloy having either metal as its maincomponent, for example, can be used so as to be suitable for externalconnection by wire bonding, or the like.

The protective film 15 has light transmittance and insulatingproperties, and is a film that covers substantially entirely the upperand a portion of side faces of the light emitting element 1, excludingside faces and a bottom faces of the substrate 11. The protective film15 also has openings 15 n and 15 p on the upper faces of the n-sideelectrode 13 and the pad electrode 142, respectively, which are theregions for external connection. For the protective film 15, forexample, an oxide, such as SiO₂, TiO₂, Al₂O₃, or the like, a nitridesuch as SiN or the like, or a fluoride such as MgF₂ or the like, cansuitably be used.

In the light emitting element 1, moreover, the positions and shapes ofthe n-side electrode 13 and p-side electrode 14, and the stackingstructure are not limited to those employed in this embodiment, and canbe suitably determined.

The light emitting element 1 is not limited to those having both then-side electrode 13 and the p-side electrode 14 on one face like thisembodiment, and it may have the n-side electrode 13 on one face and thep-side electrode 14 on the other face. In this case, for the firstbonding member 31, a conductive bonding material, for example, metalsuch as solder, an anisotropic conductive paste made of a thermosettingresin containing conductive particles, or the like, can be used toelectrically connect one of the electrodes disposed on the mounting faceside of the light emitting element 1 to the wiring pattern disposed onthe upper face of the mounting substrate 2. The other electrode disposedon the opposing face of the light emitting element 1 can be electricallyconnected to the wiring pattern by wire bonding.

The surface of the light emitting element 1 to be joined with a bondingmember 3 preferably allows for the bonding member 3 to effect goodwetting. For example, in the cases where the bonding member 3 is a metalmaterial, such as solder, to be joined to the lower face of the lightemitting element 1, the lower face of the light emitting element 1preferably has a metal film which has Au or Sn as the outermost surface.When the first bonding member 31 is metal such as solder, in particular,disposing a metal film in one section of the lower face of the lightemitting element 1 can bond the light emitting element 1 and the firstbonding material 31 at the section where the metal film is formed.Moreover, disposing the metal film inward from the perimeter of thelight emitting element 1 being surrounded by a material with which thefirst bonding member 31 has poor wetting (for example, sapphire) canreduce adhering the first bonding member 31 to the outer edge of thelight emitting element. By bonding the light emitting element using thesecond bonding member 32 primarily made of a thermosetting resin at theouter region where the first bonding material 31 hardly adheres to, thelight emitting device 100 according to this embodiment can be easilyproduced.

Returning to FIGS. 1, 2A and 2B, the explanation of the construction ofthe light emitting device 100 will be continued.

The mounting substrate 2 in this embodiment is a substrate for mountingelectronic components such as the light emitting elements 1, andincludes a rectangular flat sheet shaped base 21, and a wiring patterndisposed on an upper face of the base 21 comprising a positive electrode22, a negative electrode 23, and a relay wiring section 24.

It is preferable to use an insulating material for the base 21, and ispreferable to use a material which does not allow the light emitted fromthe light emitting elements 1 or the external light to transmittherethrough. It is also preferable to use a material having strength tosome extent. Examples include ceramics (Al₂O₃, AlN, or the like), andresins, such as phenol resins, epoxy resins, polyimide resins, BT resin(bismaleimide triazine resin), polyphthalamide (PPA), or the like. Theupper face of the base 21, at least a region where the light emittingelements 1 are mounted, preferably have good light reflectivity. It ispreferable to dispose a light reflecting layer employing, for example,metal, such as Ag, Al, or the like, or a white resin containing whitepigments.

The positive electrode 22 has a pad section 22 a for connecting to anexternal power supply, and a wiring section 22 b for wire connectingwith the light emitting elements 1 and the protective element 5. Thewiring section 22 b is disposed so as to extend from the pad section 22a provided at the upper left region, and along the left side of therectangular region in which the light emitting elements 1 are arranged.

The negative electrode 23 has a pad section 23 a for connecting to anexternal power supply, and a wiring section 23 b for wire connectingwith the light emitting elements 1 and the protection element 5. In thevicinity of the wiring section 23 b, a cathode marking CM is provided toidentify the negative electrode. The wiring section 23 b is disposed soas to extend from the pad section 23 a provided at the lower rightregion, and along the lower side and the left side of the rectangularregion in which the light emitting elements 1 are arranged.

The relay wiring section 24 is provided to relay the wiring between thepositive electrode 22 and the negative electrode 23, and is disposed soas to extend along the right side of the rectangular region in which thelight emitting elements 1 are arranged.

The wiring section 22 b, the wiring section 23 b, and the relay wiringsection 24 are electrically connected to the light emitting elements 1using wires 4 as described above. The protective element 5 ismechanically and electrically connected to one end of the wiring section22 b using a conductive bonding member such as solder, and electricallyconnected to the wiring section 23 b using a wire 4. For the wiringpattern comprising the positive electrode 22, the negative electrode 23,and the relay wiring section 24, a metal film made of, for example, Cu,Au, Ag, Al, or the like, can be used.

The positive electrode 22, the negative electrode 23, and the relaywiring section 24 are not limited to those exemplified in FIG. 2A, andthe wiring pattern can be suitably determined in accordance with themanner in which the light emitting elements 1 are arranged orelectrically connected.

In this embodiment, the light emitting elements 1 are bonded on the base21, but are not limited to this. For example, they may be mounted on thepositive electrode 22, the negative electrode 23, the relay wiringsection 24, or any other metal material disposed on the base 21. Themounting substrate 2 in this embodiment is constructed with conductiveelectrodes disposed on the upper face of the insulating base 21, but isnot limited to this. The mounting substrate 2 may be one which has nobase 21 (i.e., constructed only with electrodes).

The bonding member 3 provided for bonding the light emitting elements 1to the upper face of the mounting substrate 2 comprise a first bondingmember 31 and a second bonding member 32. In this embodiment, the lightemitting elements 1 are bonded to the mounting substrate 2 using thefirst bonding member 31 so as to be positioned with high precision inthe first bonding step S103 (see FIG. 4), and then bonded to themounting substrate 2 using the second bonding member 32 in the secondbonding step S104 (see FIG. 4).

The first bonding member 31 is disposed in an area contained within thelower face of the substrate 11, which is the mounting face of each lightemitting element 1, in a plan view. The first bonding member 31 isdisposed between the mounting substrate 2 and the light emitting element1 in a liquid or paste form, and then exerts its bonding strength whenhardened by heat treatment or the like. For the first bonding member 31,metals, thermosetting resins, thermosetting resins containing metalparticles, or the like, can be suitably used.

Now, in the case where the second bonding member 32 is a material thatexerts its bonding strength when hardened by heat treatment, and thefirst bonding member 31 is of the nature that would melt or remelt, thematerials employed as the first and second bonding, members 31 and 32are selected so that the melting temperature of the first bonding member31 is higher than the heating temperature for the second bonding member32.

The second bonding member 32 is disposed at least in one section of theouter edge of the mounting face of each light emitting element 1. Thesecond bonding member 32 can enhance the bonding between the lightemitting element 1 and the mounting substrate 2. The second bondingmember 32 is disposed at the outer edges of the light emitting element 1in a liquid or paste form, and then exert its bonding strength whenhardened following heat treatment or the like. For the second bondingmember 32, metals, thermosetting resins, thermosetting resins containingmetal particles, or the like, can suitably be used.

In this embodiment, as shown in FIG. 2B, the second bonding member 32 isdisposed contiguously between the light emitting elements 1. However,the configuration of the second bonding member 32 is not limited tothis, and can be disposed in isolation per light emitting element 1. Inother words, the second bonding member 32 can be disposed under eachlight emitting element 1 isolated from one another.

The second bonding member 32 preferably bonds each light emittingelement 1, for example, in at least 99%, at least 85%, or at least 50%of the lower face area of the light emitting element 1.

Examples of the combinations of the first and second bonding materials31 and 32 will be explained with reference to TABLE 1. TABLE 1exemplifies the combinations of materials for the first and secondbonding members 31 and 32. The combinations of the first and secondbonding members 31 and 32 include those that combine two metals, thosethat combine metal and a thermosetting resin, those that combine twothermosetting resins, and those that combine a metal-containingthermosetting resin and a thermosetting resin. Moreover, the materialsfor the first and second bonding members 31 and 32 are selected so thatthe bonding achieved by the first bonding member 31 can be retainedduring the heat treatment to harden the second bonding member 32.

TABLE 1 Combination First Bonding Second Bonding Combination No. MemberMember Type 1 AuSn paste AuSn paste Metal-Metal (Au 78:Sn 22) (Au 1:Sn9) 2 AuSn paste SnCu paste (Au 78:Sn 22) 3 AuSn paste SnCu paste (Au1:Sn 9) 4 AuSn paste Silicone resin Metal-Resin (Au 78:Sn 22) 5 AuSnpaste Silicone resin (Au 1:Sn 9) 6 SnCu paste Silicone resin 7 AuSnpaste Epoxy resin (Au 78:Sn 22) 8 AuSn paste Epoxy resin (Au 1:Sn 9) 9SnCu paste Epoxy resin 10 Silicone resin Silicone resin Resin-Resin 11Silicone resin Epoxy resin 12 Epoxy resin Silicone resin 13 Epoxy resinEpoxy resin 14 Ag paste Silicone resin Metal Resin- 15 Ag paste Epoxyresin Resin

Combination Nos. 1-3 shown in TABLE 1 combine a first metal for thefirst bonding member 31 and a second metal for the second bonding member32, both having a relatively low melting point (for example, about 300°C. or lower), such as solder.

These metals bond together the light emitting elements 1 and themounting substrate 2 by being cooled to harden (solidify) after beingmelted by heat treatment. Metals may lose their bonding ability ifremelted by being heated above their melting points even after they areonce hardened. Accordingly, when combining two metals, selections may bemade so that the melting point of the metal selected as the secondbonding member 32 (the first temperature) is lower than the meltingpoint of the metal selected as the first bonding member 31 (the secondtemperature). This enables the heat treatment for the second bondingmember 32 to be performed under the temperature condition that allowsthe first bonding member 31 to retain its bonding ability withoutremelting.

For the metals employed as the first and second bonding members 31 and32, for example, AuSn-based low melting point (217° C.) eutecticcomposition (Au 1:Sn 9) solder, AuSn-based high melting point (278° C.)eutectic composition (Au 78:Sn 22) solder, SnCu-based lead-free solderspecified by JIS Z 3283:2006, or the like, can suitably be used. Here,composition Au 1:Sn 9 represents 10 mass % Au and 90 mass % Sn, andcomposition Au 78:Sn 22 represents 78 mass % Au and 22 mass % Sn.

When using metal for both the first and second bonding members 31 and32, the first and second bonding members 31 and 32 in a liquid or pasteform before being hardened may be used as the first and second pastes,respectively, by having a solvent, such as a flux, contain particles ofthe metals described above.

Combination Nos. 4-9 shown in TABLE 1 combine a relatively low meltingpoint (preferably about 300° C. or lower) metal such as solder for thefirst bonding member 31, and a thermosetting resin for the secondbonding member 32.

For the first bonding member 31, the same metals described in connectionwith the combination Nos. 1-3 can be used. For the second bonding member32, a thermosetting resin having high light transmission, heatresistance, weather resistance, and light resistance is preferably used.Examples of such thermosetting resins include silicone resins, siliconemodified resins, epoxy resins, epoxy modified resins, urea resins,phenol resins, acrylic resins, or hybrid resins containing at least oneof these resins. Among all, silicone or epoxy resins are preferable. Thecuring temperatures for these materials are about 120-180° C.

When combining a metal and a thermosetting resin, moreover, selectionsmay be made so that the curing temperature of the thermosetting resinselected as the second bonding material 32 is lower than the meltingpoint of the metal selected as the first bonding member 31. This enablesthe curing of the second bonding member 32 to be performed under thetemperature condition that allows the first bonding member 31 to retainits bonding ability without remelting.

Combination Nos. 10-13 shown in TABLE 1 combine two thermosetting resinsas the first and second bonding members 31 and 32. Thermosetting resinsbond together the light emitting elements 1 and the mounting substrate 2when cured by heat treatment, but once cured, they can retain theirbonding ability without remelting even if reheated. Accordingly, thethermosetting resins used as the first and second bonding members 31 and32 may have the same curing temperature, or either may have a highercuring temperature.

Combination Nos. 14 and 15 shown in TABLE 1 combine a metal pasteprepared by having a thermosetting resin contain metal particles havinga relatively high melting point (at least higher than the curingtemperature of the thermosetting resin) used as the first bonding member31, and a thermosetting resin used as the second bonding member 32. Forthe metal, Ag or Cu, for example, can be employed. The bonding abilityof the first bonding member 31 is exerted by the curing of thethermosetting resin, but the metal particles contained therein allow theheat to transfer from the light emitting elements 1 to the mountingsubstrate 2, thereby reducing the temperature increase in the lightemitting elements 1. Imparting conductivity to the first bonding member31 by having it contain metal particles can also achieve electricalconnection between the light emitting elements 1 and the mountingsubstrate 2.

Even when heat treatment is performed to cure the second bonding member32, the first bonding member 31 can retain its bonding ability becauseit contains a thermosetting resin. Accordingly, the thermosetting resinscombined as the first and second bonding members 31 and 32 may have thesame curing temperature, or either may have a higher curing temperature.

For the thermosetting resins for the first and second bonding members 31and 32, those cited in the combination Nos. 10-13 can be used.

In the cases where one of the electrodes of the light emitting elements1 is disposed on the mounting face side, the light emitting elements 1can be mounted on, and electrically connected to, the mounting substrate2 by being bonded to the electrode of the mounting substrate 2 using ametal, such as solder, or a conductive adhesive material made of ametal-containing thermosetting resin as the first bonding member 31.

In the cases where a light transmitting material, such as an epoxy orsilicone resin, is used as the first bonding member 31 and/or the secondbonding member 32, the thermosetting resin may contain light reflectingparticles. Imparting light reflectivity to the first bonding member 31and/or the second bonding member 32 by having it contain lightreflecting particles can increase the light extraction efficiency fromthe upper face side of the light emitting elements 1, and as a result,can increase the light extraction efficiency of the light emittingdevice 100. For the light reflecting particles, a substance having arefractive index that is significantly different from that of the lighttransmitting base material is preferable, and for example, TiO₂, Al₂O₃,ZrO₂, MgO, or the like, can suitably be used.

The light emitting device 100 in this embodiment includes wires 4. Thewires 4 are used to electrically connect the light emitting elements 1with one another, and between the light emitting elements 1 and thewiring sections 22 b, 23 b, and the relay wiring section 24. The wire 4is also used to electrically connect a protective element 5 to thewiring section 23 b. For the wires 4, metal wires having goodconductivity, such as Cu, Au, Ag, Al, or any alloy having these metalsas the main components can suitably be used.

The light emitting device 100 in this embodiment includes a protectiveelement 5. The protective element 5 is disposed for the purpose ofprotecting the light emitting elements 1 from electrostatic discharge,for example. For the protective element 5, for example, a Zener diodeconnected to the light emitting elements 1 in reverse polarity betweenthe positive electrode 22 and the negative electrode 23 can be used. Avaristor, resistor, capacitor, or the like, can also be used as theprotective element 5.

One of the electrodes of the protective element 5 in this embodiment iselectrically connected to the wiring section 22 b by being joinedthereon using a conductive bonding material such as solder. The otherelectrode of the protective element 5 is electrically connected to thewiring section 23 b using a wire 4.

The light emitting device 100 in this embodiment includes a lightreflector 6. The light reflector 6 is formed to cover the relay wiringsection 24, the protective element 5, a portion of each of the wiringsections 22 b and 23 b, and a portion of each of the wires 4 connectingthese. With this arrangement, even when the wiring sections 22 b and 23b, the relay wiring section 24 and the wires 4 are formed using Au whichreadily absorbs light, the light emitted from the light emittingelements 1 is reflected by the light reflector 6 and an amount of lightreaching the wiring sections 22 b and 23 b, the relay wiring section 24,or the wires 4 can be reduced. Accordingly, loss of emitted light can bereduced, and the light extraction efficiency of the light emittingdevice 100 can be increased. Furthermore, covering the relay wiringsection 24, the protection element 5, a portion of each of the wiringsections 22 b and 23 b, and a portion of each of the wires 4 connectingthese with the light reflector 6 can protect these components from dust,moisture, external force, or the like.

The light reflector 6 is preferably formed on the mounting substrate 2in a quadrangle frame shape so as to surround the region in which thelight emitting elements 1 are arranged. The light reflector 6 formed tosurround the region in which the light emitting elements 1 are arrangedin this manner can upwardly reflect the light emitted transversely fromthe light emitting elements 1 located at the top, bottom, right, andleft ends shown in FIG. 2A and travels towards the periphery of theregion in which the light emitting elements 1 are arranged. This canreduce loss of emitted light, and thus can increase the light extractionefficiency of the light emitting device 100.

For the light reflector 6, a resin material having good transmittanceand insulation properties, such as an epoxy or silicone resin, forexample, can suitably be used. Light reflectivity can be preferablyimparted by dispersing in the base resin material light reflectingparticles, such as TiO₂, Al₂O₃, ZrO₂, or MgO, for example.

The light emitting device 100 in this embodiment includes a sealingmember 7. The sealing member 7 is disposed to fill the recess, which isa region surrounded by the light reflector 6, to protect the lightemitting elements 1, the protection element 5, and the wires 4 fromdust, moisture, external force, or the like.

For the sealing member 7, materials having good light transmission,weather resistance, and light resistance are preferable, and forexample, silicone resins, epoxy resins, urea resins, or the like cansuitably be used. These resin materials, moreover, may appropriatelycontain a wavelength converting substance (phosphor), a coloring agent,a light diffusing material, and any other filler. The sealing member 7may also be heaped up to a bullet or convex lens shape so that thesealing member 7 can function as a lens.

Operation of the Light Emitting Device

Next, the operation of the light emitting device 100 in this embodimentwill be explained with reference to FIGS. 2A to 3.

The light emitting elements 1 emit light when power is supplied via thewires 4 and the relay wiring section 24 from an external power supplywhich connected to the positive electrode 22 and the negative electrode23 of the mounting substrate 2. The light emitted upwardly from thelight emitting elements 1 is extracted from the upper face through thesealing member 7. The light emitted transversely from the light emittingelements 1 is reflected by the side faces of the light reflector 6, andis extracted from the upper face through the sealing member 7. The lightemitted downwardly from the light emitting elements 1 is reflected bythe first bonding member 31, the second bonding member 32, or the base21, and is extracted from the upper face through the sealing member 7.

Since each light emitting element 1 is precisely positioned and bondedby the first bonding member 31 on the mounting substrate 2, the lightemitting device 100 can achieve good light distribution characteristics.

Method for Producing the Light Emitting Device

The method for producing the light emitting device according to thisembodiment will be explained next with reference to FIGS. 4 to 8C. Themethod for producing the light emitting device according to thisembodiment includes a light emitting element preparation step S101, amounting substrate preparation step S102, a first bonding step S103, asecond bonding step S104, a wiring step S105, a light reflector formingstep S106, and a sealing step S107.

The first bonding step S103 includes a first bonding member disposingstep S103 a, a light emitting element placement step S103 b, and a firstbonding member hardening step S103 c. The Second bonding step S104includes a second bonding member disposing step S104 a and a secondbonding member hardening step S104 b.

The light emitting element preparation step S101 is a step of preparinglight emitting elements 1 having the structure such as that shown inFIGS. 3A and 3B. An example of the production method for the lightemitting elements 1 will be explained below.

In more specific terms, first, on the upper face of a substrate 11, suchas sapphire, a semiconductor stack 12 is formed by sequentially stackingan n-type semiconductor layer 12 n, an active layer 12 a, and p-typesemiconductor layer 12 p using a semiconductor material, such as anitride semiconductor, by MOCVD or the like. The n-type semiconductorlayer 12 n is then exposed in one region of the surface of thesemiconductor stack 12 by removing from the upper face side the p-typesemiconductor layer 12 p and the active layer 12 a entirely, and then-type semiconductor layer 12 n partially.

Then, a light transmitting electrode 141 is formed using a lighttransmitting conductive material, such as ITO, so as to coversubstantially the entire upper face of the p-type semiconductor layer 12p. A p-side electrode 14 is further formed on one upper face section ofthe light transmitting electrode 141 by forming a pad electrode 142using a metal material, such as Cu or Au. On the upper face of theexposed n-type semiconductor layer 12 n, an n-side electrode 13 isformed by forming a pad electrode 132 using a metal material, such as Cuor Au.

Next, a protective film 15 covering the entire wafer is formed using alight transmitting insulating material, such as SiO₂, so as to have theopenings 15 n and 15 p in the upper face regions of the n-side electrode13 and the pad electrode 142, respectively, for external connection.

Then, the light emitting elements 1 are separated by cutting the waferby dicing or scribing. The substrate 11 may be thinned before cuttingthe wafer by polishing the face on which the semiconductor stack 12 isnot formed.

A step of disposing a metal film at the bottom of the substrate 11 toenhance the bondability with a metal material may be included.

The mounting substrate preparation step S102 is a step of preparing themounting substrate 2 on which the wiring pattern comprising the positiveelectrode 22, the negative electrode 23, and the relay wiring section 24is formed. The wiring pattern can be formed by a subtractive process,for example, by forming a metal film across the entire upper face of thebase 21, disposing a mask covering the regions to be retained as thewiring pattern, and etching off the exposed metal film.

Either the light emitting element preparation step S101 or the mountingsubstrate preparation step S102 may precede the other, or the two stepsmay be performed in parallel. In this specification, the preparationsteps are not limited to those that produce the light emitting elements1 and the mounting substrate 2 by the processes described above, andinclude obtaining them by purchasing or the like.

The first bonding step S103 is a step of bonding the light emittingelements 1 to the mounting substrate 2 using a first bonding member 31,preferably with good positional accuracy. As described earlier, thisstep may include three steps.

In the first bonding member disposing step S103 a, as shown in FIG. 5A,an appropriate amount of the first bonding member 31 in a liquid orpaste form is supplied by a dispensing process, or the like, within theprescribed individual disposition areas 1 a on the upper face of themounting substrate 2 where the light emitting elements 1 will be placed.The appropriate amount in this context means the amount that would notcause the liquid or paste first bonding member 31 to ooze out of themounting face of each light emitting element 1 when pressed to spreadout by placing the light emitting element 1 on the first bonding member31. Moreover, the first bonding member 31 is supplied in the amount thatis sufficient to achieve the bonding strength at which the lightemitting elements 1 are not separated from the mounting substrate 2 ordislocated at least until the light emitting elements 1 are firmlybonded in the second bonding step S104. The first bonding member 31 ispreferably placed roughly in the center of each light emitting element 1in a plan view.

Next, in the light emitting element placement step S103 b, as shown inFIG. 5B, the light emitting elements 1 are placed using collets, forexample, in the individual disposition areas 1 a on the upper face ofthe mounting substrate 2 via the first bonding member 31.

Then in the first bonding member hardening step S103 c, as shown in FIG.5C, the light emitting elements 1 and the mounting substrate 2 arebonded together by allowing the first bonding member 31 to harden byperforming heat treatment using a heating apparatus 201.

In the cases where the first bonding member 31 before hardening is apaste combining a solvent such as a flux and metal particles such assolder, the light emitting elements 1 and the mounting substrate 2 arebonded together when the metal particles are melted by heating to themelting point or higher and subsequently hardened (solidified) bycooling.

Cooling may be accomplished by using a cooling apparatus, or by naturalcooling by letting it stand at room temperature or lower.

In the cases where the first bonding member 31 before hardening is athermosetting resin, or a material containing relatively high meltingpoint metal particles and a thermosetting resin, such as an Ag paste,the first bonding member 31 can be hardened by heating to at least thepre-cure temperature of the thermosetting resin. In other words, thecuring of the first bonding member 31 in the first bonding memberhardening step S103 c is sufficient as long as the light emittingelements 1 and the mounting substrate 2 are joined together, whichincludes pre-curing.

This step may also be performed under the full cure temperature andheating time conditions to fully cure the first bonding member 31.

A heating apparatus 201 can be appropriately selected in accordance withthe type of the first bonding member 31 and the heating temperaturerequired for hardening the material. For example, a reflow furnace, anoven, an infrared heater, a laser heater, a hot air heater, or a sheetheater capable of holding the mounting substrate 2 thereon can be used.

In the first bonding step S103 in this embodiment, the first bondingmember 31 is placed in the areas contained within the mounting faces ofthe light emitting elements 1 in a plan view. The light emittingelements 1 can be positioned with high precision without beingsignificantly dislocated from the prescribed individual dispositionareas 1 a, even when the first bonding member 31 is in the liquid orpaste state before hardening, in the state of reduced viscosity duringheat treatment, or in the molten state in the case the first bondingmember 31 is a low melting point metal. By hardening the first bondingmember 31, the light emitting elements 1 can be bonded to the mountingsubstrate 2 while being precisely positioned.

The second bonding step S104 is a step of bonding together the outeredges of the light emitting element 1 and the mounting substrate 2 usingthe second bonding member 32 subsequent to the first bonding step S103.As described earlier, this step includes two steps.

First, in the second bonding member disposing step S104 a, as shown inFIG. 6A, the second bonding member 32 in a liquid or paste form issupplied by using a dispenser, or the like, to be positioned so as tocover at least one section of the outer edges of the light emittingelements 1. The second bonding member 32 is preferably disposed tosurround the entire perimeter of the outer edge of each light emittingelement 1 so that the light emitting element 1 and the mountingsubstrate 2 are more firmly bonded together. The second bonding member32, moreover, is preferably disposed so as to come into contact with thefirst bonding member 31, and surround the entire perimeter of the firstbonding member 31. The second bonding member 32 may be disposed inisolation per light emitting element 1, but as shown in FIG. 6A,disposing it to fill the spaces between the light emitting elements 1can more firmly bond the light emitting elements 1 as a whole and themounting substrate 2 together.

In the cases where the plural light emitting elements 1 are arranged atrelatively narrow intervals, such as 1 mm or less, for example, bydispensing drops of an appropriate amount of the second bonding member32 at the corners formed by the light emitting elements 1 as shown inFIG. 7A and letting it stand, the second bonding member 32 can bedisposed to surround the entire perimeter of the outer edges of thelight emitting elements 1 as shown in FIG. 7B. At this time, byadjusting the viscosity of the second bonding member 32 in accordancewith the intervals at which the light emitting elements 1 are arranged,the second bonding member 32 can be spread around the light emittingelements 1 and into the spaces therebetween by gravitational force andcapillary action as shown in FIG. 7B.

The appropriate amount in this context refers to the amount that allowsthe second bonding member 32 to spread around some the light emittingelements 1, preferably the entire outer edges of the light emittingelements 1.

Furthermore, by dispensing the second bonding member 32 while placingthe mounting substrate 2 on which the light emitting elements 1 arebonded by the first bonding member 31 under reduced pressure, the secondbonding member 32 can efficiently penetrate the gaps between the lowerfaces of the light emitting elements 1 and the upper face of themounting substrate 2 even when the gaps are narrow. This can increasethe bonding strength between the light emitting elements 1 and themounting substrate 2.

Next, in the second bonding member hardening step S104 b, as shown inFIG. 6B, heat treatment is performed using a heating apparatus 201 toharden the second bonding member to join the light emitting elements 1and the mounting substrate 2 together. For the heating apparatus 201,any of those cited for the first bonding member hardening step S103 ccan be employed in accordance with the type of the second bonding member32 and the required heating temperature for hardening. The heattreatment in the second bonding member hardening step S104 b isperformed at the temperature capable of hardening the second bondingmember 32 employed, as in the case of the first bonding member hardeningstep S103 c.

In the cases where the first bonding member 31 is a metal material thatis melted by heat treatment, the heat treatment in the second bondingmember hardening step S104 b is preferably performed at a lowertemperature than that used in the heat treatment in the first bondingmember hardening step S103 c so as not to remelt the first bondingmember 31.

When the first bonding member 31 is a metal which is melted by heattreatment, as in the cases of Combination Nos. 1-3 shown in TABLE 1, ametal having a lower melting point than the metal used as the firstbonding member 31 is employed as the second bonding member 32.Accordingly, the heat treatment in the second bonding member hardeningstep S104 b is performed at a temperature which can melt the metalemployed as the second bonding member 32, but does not melt the metalused as the first bonding member 31. This enables the first bondingmember 31 to retain its bonding ability while enabling the secondbonding member 32 to firmly bond the light emitting elements 1 and themounting substrate 2 together without allowing the light emittingelements 1 to be separated or dislocated.

When the first bonding member 31 is a metal which is melted by heattreatment, as in the cases of Combination Nos. 4-9 shown in TABLE 1, athermosetting material that can be fully cured at a lower temperaturethan the melting point of the metal used as the first bonding member 31is preferably employed as the second bonding member 32. Accordingly, theheat treatment in the second bonding member hardening step S104 b isperformed at a temperature that can fully cure the thermosetting resinemployed as the second bonding member 32, but does not melt the metalused as the first bonding member 31. This enables the first bondingmember 31 to retain its bonding ability while enabling the secondbonding member 32 to firmly bond the light emitting elements 1 and themounting substrate 2 together without allowing the light emittingelements 1 to be separated or dislocated.

When the first bonding member 31 is a thermosetting resin or athermosetting resin containing a metal having a relatively high meltingpoint, as in the cases of Combination Nos. 10-13 or 14-15 shown in TABLE1, the first bonding member 31 is not remelted by heat treatment. Forthis reason, the thermosetting resin employed as the second bondingmember 32 may have the same curing temperature as that of thethermosetting resin used as the first bonding member 31, or higher orlower curing temperature. In these cases, moreover, the first bondingmember 31 retains its bonding ability regardless of the heat treatmenttemperature in the second bonding member hardening step S104 b, and thusthe second bonding member 32 can firmly bond the light emitting elements1 and the mounting substrate 2 together without allowing the lightemitting elements 1 to be separated or dislocated.

In the cases where the first bonding member 31 is pre-cured in the firstbonding member hardening step S103 c, moreover, it is preferable to usea thermosetting resin as the first bonding member 31 that can be fullycured at the heating temperature used for fully curing the thermosettingmaterial employed as the second bonding member 32 in the second bondingmember hardening step S104 b. This can fully cure both thermosettingmaterials employed as the first and second bonding members 31 and 32,and as a result, can more firmly bond the light emitting elements 1 andthe mounting substrate 2 together.

This embodiment includes a wiring step S105. As shown in FIG. 8A, thisis a step of disposing wires between the wiring sections 22 b, 23 b, therelay wiring section 24, and the n-side electrode 13 and the p-sideelectrode 14 of each light emitting element 1 so as to complete thecircuit described previously using a wire bonder subsequent to thesecond bonding step S104.

Moreover, during the wiring step S105, or before or after the wiringstep S105, one of the electrodes of the protection element 5 is bondedto the wiring section 22 b using a conductive bonding member, such assolder, and subsequently, the other electrode of the protection element5 and the wiring section 23 b are connected by a wire 4 using a wirebonder.

This embodiment includes a light reflector forming step S106. As shownin FIG. 8B, this is a step of forming a frame-shaped light reflector 6along the perimeter of the region in which the light emitting elements 1are arranged on the mounting substrate 2 subsequent to the wiring stepS105. The light reflector 6 is disposed to cover the wiring sections 22b and 23 b, the relay wiring section 24, and some portions of the wires4.

The light reflector 6 can be formed with any of the resin materialsmentioned earlier using, for example, a dispenser. The light reflector 6can also be formed by silk screen printing, ink-jet printing, or thelike.

This embodiment includes a sealing step S107. As shown in FIG. 8C, thisis a step of sealing the light emitting elements 1 and the wires 4 byfilling the inside of the frame-shaped light reflector 6 with a sealingmember 7 subsequent to the light reflector forming step S106. Thesealing member 7 can be formed by dispensing any of the resin materialsmentioned in the forgoing to the inner region of the light reflector 6by potting or the like. The sealing member 7 can also be formed bymolding using a die.

The light emitting device 100 in this embodiment can be produced by thesteps explained above.

INDUSTRIAL APPLICABILITY

The method for producing the light emitting devices according to thisdisclosure are applicable to produce light emitting devices for variouslight sources, including liquid crystal display backlights, lightingfixtures, large sized displays, various display devices foradvertisements and destination signs, image pickup devices used indigital video cameras, facsimiles, copiers, and scanners, as well asprojectors.

What is claimed is:
 1. A method for producing a light emitting device,the method comprising: a first bonding step comprising: disposing afirst bonding member in a liquid or paste form on an upper face of amounting substrate, placing a light emitting element on the mountingsubstrate such that the first bonding member is located between amounting face of the light emitting element and the upper face of themounting substrate, wherein the light emitting element includes anelectrode at an upper face of the light emitting element, and hardeningthe first bonding member thereby bonding the light emitting element tothe mounting substrate such that, in a plan view, an entirety of thefirst bonding member is contained within an area of the mounting face ofthe light emitting element; and a second bonding step comprising:disposing a second bonding member in a liquid or paste form on the upperface of the mounting substrate such that, in a plan view, the secondbonding member extends around a periphery of the first bonding member,and hardening the second bonding member.
 2. The method according toclaim 1, wherein the first bonding step and the second bonding step bothcomprise heating.
 3. The method according to claim 2, wherein: the firstbonding member, before hardening, is a first paste containing particlesof a first metal having a melting point at a first temperature, thesecond bonding member, before hardening, is a second paste containingparticles of a second metal having a melting point at a secondtemperature lower than the first temperature, and in the second bondingstep, the sub-step of hardening the second bonding member comprisesheating at a temperature that is higher than the second temperature andlower than the first temperature.
 4. The method according to claim 2,wherein: the first bonding member, before hardening, is a pastecontaining particles of a metal having a melting point at a firsttemperature, the second bonding member comprises a thermosetting resin,and in the second bonding step, the sub-step of hardening the secondbonding member comprises heating at a temperature that is lower than thefirst temperature.
 5. The method according to claim 2, wherein: thefirst bonding member and the second bonding member each comprise athermosetting resin, and in the first and second bonding steps, thesub-steps of hardening the first bonding member and hardening the secondbonding member both comprise heating to thereby cure the thermosettingresins.
 6. The method according to claim 5, wherein: in the firstbonding step, heating is performed at least at a temperature capable ofpre-curing the thermosetting resin contained in the first bondingmember, and in the second bonding step, heating is performed at least ata temperature capable of fully curing the thermosetting resin containedin the second bonding member.
 7. The method according to claim 5,wherein: the first bonding member contains metal particles and athermosetting resin, and the thermosetting resin contained in the firstbonding member is cured in the first bonding step.
 8. The methodaccording to claim 6, wherein: the first bonding member contains metalparticles and a thermosetting resin, and the thermosetting resincontained in the first bonding member is cured in the first bondingstep.
 9. The method according to claim 3, wherein the first metal andthe second metal are each selected from among AuSn-based and SnCu-basedsolders.
 10. The method according to claim 4, wherein: the metal isselected from among AuSn-based and SnCu-based solders, and thethermosetting resin is selected from among silicone resins and epoxyresins.
 11. The method according to claim 5, wherein the thermosettingresin contained in the first bonding member and the thermosetting resincontained in the second bonding member are each selected from amongsilicone resins and epoxy resins.
 12. The method according to claim 7,wherein: the metal is selected from among Ag and Cu, and thethermosetting resin contained in the first bonding member and thethermosetting resin contained in the second bonding member are eachselected from among silicone resins and epoxy resins.
 13. The methodaccording to claim 8, wherein: the metal is selected from among Ag andCu, and the thermosetting resin contained in the first bonding memberand the thermosetting resin contained in the second bonding member areeach selected from among silicone resins and epoxy resins.
 14. Themethod according to claim 1, wherein: the first bonding step comprises:disposing a plurality of the first bonding members on the upper face ofthe mounting substrate, placing a plurality of the light emittingelements on the mounting substrate such that each first bonding memberis located between a mounting face of each respective light emittingelement and the upper face of the mounting substrate, and hardening theplurality of first bonding members thereby bonding the plurality oflight emitting elements to the mounting substrate such that, in a planview, an entirety of each first bonding member is contained within anarea of the mounting face of each respective light emitting element; andthe second bonding step comprises disposing the second bonding membersuch that, in a plan view, the second bonding member extends around theperipheries of all of the first bonding members.